说明：  本程序实现了一个信号发生器。此信号发生器是由两个完全相同的可自加载加法计数器LCNT8组成，它的输出信号的高低电平脉宽可分别由两组8位预置数进行控制。
(This procedure implements a signal generator. This signal generator is made up of two identical adder can be loaded from the counter LCNT8 composition, and its output signal high-low pulse width can be preset by the two groups of eight control number.)